Convenience packaging, particularly for foodstuffs and bulk materials, frequently involves the use of bags or pouches. These bags can be advantageously constructed with side or bottom gussets to make them able to be set upright on a horizontal supporting surface, for filling, display or storage. It is common to refer to bags with bottom expansion panels and sealed side and top edges as ‘pouches’.
More recently, bags have been produced with expansion panels at both top and bottom, and vertical side seals. Examples of these bags are marketed under the trade name “Flex-Can”, for example, and are known for their ability to be conveniently stacked one on top of another, like cans. Both the top and bottom panels of these bags expand substantially and simultaneously as the bags are filled, such that the sides of the bag separate at both top and bottom, in some cases remaining generally parallel and vertical. As filled, the bag and its contents can exhibit significant structural stability, enabling stacking and convenient handling, with very little head space above the contents.